Riot is playing with me

I dont understand why this could happen. I just started a ranked game and i watched a example build on internet and when i tried to open my first page of league of legends the game itself started to repair the files after 4 minutes of repairing i got a message from riot ''LeaverBuster'' How the heck can i fix this because i am restricted in 5 games 20 minutes each. Come on Riot !!!!